Public awareness of environmental issues has steadily increased in recent years. As a result, the general public now demands a quality environment with clean air in which to live, work and entertain. Various types of air filtration systems are used in residential and commercial buildings to improve the quality of the air. One commonly used filter configuration for commercial applications is a “IV-bank” arrangement of planar air filters, because the V-bank provides twice the filter area of a planar air filter in the same air passage.
Electrostatic V-bank air filters are constructed from a pair of electrostatic air filters supported by V-shaped side panels installed in an air-handling system. The pair of air filters share the air cleaning load of air drawn through an air intake at a wide end of the V-shaped side panels. Because of their air cleaning efficiency and ease of maintenance, there is a rapidly increasing demand for electrostatic V-bank air filters. They have become particularly popular in public places with significant air quality problems, such as casinos and bars, where cigarette smoke is of particular concern. They are also gaining acceptance in animal husbandry where they are used for odor and/or disease control in livestock and poultry housing. They are also expected to gain acceptance in office, small commercial buildings and residential buildings and private homes, where they can contribute to air quality.
An example of electrostatic V-shaped filter banks is described in the Applicant's U.S. Pat. No. 6,294,004 which issued on Sep. 25, 2001. The V-bank air filters are assembled from two side panels, perforated top and bottom plates, a narrow end wall and include an open wide end for the intake of air to be filtered. A pair of enclosure plates are pivotally mounted to the side panels in a parallel relationship with the respective top and bottom plates in order to form a pair of rectangular enclosures for respectively supporting electrostatic filter pads. The enclosure plates pivot open for removal and replacement of the filter pads. The side panels, top and bottom plates and rear wall are made from sheet metal blanks using cutting, bending and stamping processes. Mounting peripheral edges are provided at the open wide end for installation of the structure within an air handling system. When used in large air handling systems for commercial buildings which usually include ducts sized for walk-in maintenance, this V-shaped filter bank is easy to install, and maintain. However, installation and maintenance of these V-bank electrostatic air filters in residential and small commercial air handling systems is not straightforward and may require extensive modification to an air handling system.
In another aspect of air filtration technology, the airborne transmission of disease organisms, especially respiratory disease organisms, has long been recognized as a serious problem. Health care authorities and biologists have now become acutely aware of the problem with the evolution of antibiotic-resistant strains of Streptococcus and Tuberculosis, for example. It is well known that many diseases caused by both bacteria and viruses are primarily transmitted from host to host by air currents. Therefore, germicidal air filters have been invented and have proven to be effective in removing micro-organisms from the air and destroying them. Examples of such filters are described in U.S. Pat. No. 5,330,722 which issued on Jul. 19, 1994 to Pick and has subsequently been assigned to the Applicant. The germicidal air filtration systems described in that patent are principally suitable for permanent or semi-permanent installations.
As another example, a portable germicidal air filter is described in U.S. Pat. No. 5,837,207 which issued on Nov. 17, 1998 to Summers and is also assigned to the Applicant. The light-weight portable germicidal air filter for home and personal use described in that patent includes a cabinet that houses an electrostatic air filter, and ultraviolet lamp with a parabolic reflector or a convex lens for focusing the ultraviolet radiation emitted by the lamp onto the upstream side of the air filter. The reflector or the lamp with the lens is constantly oscillated to systematically sweep the upstream side of the filter with germicidal levels of radiation. A fan adjacent the downstream side of the filter draws air through the filter and impels it out through air outlets in the side walls of the cabinet.
A further example of an irradiation unit is described by Summers in United States patent application publication no. US2002/100878, published on Aug. 1, 2002. The irradiation unit includes an adapter that accepts a frame for supporting an ultraviolet lamp with a reflector or a lens, for focusing the radiation on a surface. The unit may include a housing secured to one end of the frame, containing a drive motor and a cam assembly which oscillate the reflector if the radiation is to be focused on a predefined area of the surface at any given time. The unit can be quickly mounted in any orientation to practically any flat surface.
While all of these options exist, there is no known commercially available integrated air filtration unit that is adapted for use in small commercial and residential air handling systems that provides excellent air filtration with low air flow resistance and germicidal air treatment.
There is therefore a need for an integrated air filtration unit that can be easily installed or retrofitted in an air handling system used for residential or small commercial buildings, is easily serviced, and combines the benefits of both a germicidal irradiation and electrostatic air filtration system.